Power slip assembly



1965 w. H. SPlRl ETAL 3,210,821

POWER SLIP ASSEMBLY Filed Jan. 8, 1962 3 Sheets-Sheet 1 a: Nil-LY H. 5 m! 650265 H- HABY DONALD 6. PE/CE INVENTORS ATToaNEY Oct. 12, 1965 w sPlRl ET 3,210,821

POWER SLIP ASSEMBLY Filed Jan. 8, 1962 3 Sheets-Sheet 2 WILL-V H 5P?! m m GEORGE .H'. HABY In 0 DONALD 6. Pelee INVENTORS ATTORNEY Oct. 12, 1965 w. H. SPIRI ETAL POWER SLIP ASSEMBLY Filed Jan. 8, 1962 3 Sheets-Sheet 5 W/LLY HI 5Pl2/ GEORGE H. HA3) DONALD (3. PRICE INVENTORS ATToQHE Y United States Patent 3,210,821 POWER SLIP ASSEMBLY Willy H. Spiri, George H. Haby, and Donald G. Price, La Mirada, Calif., assignors to Abegg & Reinhold (10., Los Angeles, Calif., a corporation of California Filed Jan. 8, 1962, Ser. No. 168,301 14 Claims. '(Cl. 24-263) This invention relates to an improved power slip assembly, for use in association with a well drilling rotary table, and particularly for power actuating pipe gripping slips into and out of their active positions relative to such a table.

There have heretofore been devised various different types of power-slip mechanisms intended to eliminate most of the manual effort from the handling of a set of slips in making or breaking the joints of a well pipe. However, none of the these prior arrangements with which I am familiar has proven entirely satisfactory. One major disadvantage of previously proposed power slips, for example, has been the difiiculty encountered in providing for proper counterbalancing of the very substantial weight of the slips and their carrier structure, while at the same time avoiding the introduction into the apparatus of an unwanted type of movement of the slip carrier as a result of the counter-balancing action. More particularly, it is desirable that the mechanism be capable of moving the slip carrier upwardly and downwardly in a straight line vertical path, as the slips are moved into and out of the slip receiving recess in a rotary table. Prior counterbalanced slip devices have had the disadvantage that, in order to provide for counterbalancing of the weight of the slips and their carrier, it has been necessary to support the carrier on a swinging lever arrangement in a manner acting inherently to shift the carrier slightly laterally as it moves upwardly and downwardly.

A major object of the present invention is to provide a power slip assembly which is so designed as to overcome the above discussed disadvantage of prior similar arrangements, and which specifically is both counterbalanced and capable of shifting the carrier upwardly and downwardly in a precisely straight line vertical path. Thus, the advantages of both counterbalancing and straight line vertical movement are attained, in combination.

A device constructed in accordance with the invention desirably includes a support adapted to be mounted at a side of the rotary table, and to which there is movably mounted a carrier structure of a type having an arm projecting generally horizontally to a position over the rotary table. The slips are mounted to this arm at a location to properly engage the table. Certain particular features of the invention reside in the formation of the apparatus in a manner such that the counterbalancing force is exerted upwardly against the mentioned arm at a location horizontally between the support at the side of the rotary table and the point of connection of the slips to the arm. Thus, the counterbalancing force is so applied as to counteract the tendency for the weight of the slips to bend the projecting ar-m downwardly, so that the tendency for damage to the support, carrier structure, and other parts of the apparatus, by reason of the offset relationship of the slips with respect to the support, is minimized.

An additional feature or object of the invention involves the construction of a unique type of automatically opening assembly of slip elements. As wellas apparent, these pipe gripping slips are pivotally interconnected, and are urged by a spring to an opened position, to facilitate movement of the slips laterally into and out of engagement with a pipe. The assembly may be closed, against the tendency of the spring, when the slips are to be lowered into engagement with the rotary table sturcture.

The above and other features and objects of the present invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawings, in which:

FIG. 1 is a side view, partially broken away, of a power slip unit constructed in accordance with the invention;

FIG. 2 is a plan view of the FIG. 1 unit;

FIG. 3 is an enlarged fragmentary vertical section taken on line 3-3 of FIG. 2;

FIG. 4 is a fragmentary vertical section similar to a portion of FIG. 1, but showing the slips as they are being lifted upwardly out of engagement with the rotary table.

FIG. 5 is a fragmentary vertical section taken on line 55 of FIG. 2; and

FIG. 6 is a perspective View of the pipe gripping slips per se.

Reference is first made to FIG. 1, in which a conventional well drilling rotary table is represented at 10, with the power slip unit of the present invention being designated generally by the numeral 11. The drill pipe, or other well pipe to be supported by power slip unit 11 is designated 12, with the pipe gripping slips themselves (typically three in number) being designated 13a, 13b and (see FIGS. 1, 2 and 6).

The rotary table 10 is supported on a stationary base 14, and includes the usual non-rotating section 15 and the power driven rotary section 16. Suitable bearings represented at 17 are provided for mounting section 16 to turn about the main vertical axis 18 of the apparatus. The rotary table of course has a central opening through which pipe 12 extends downwardly into the well, and within this opening the rotatable section 16 of table 10 has a bushing structure typically illustrated at 19, which structure contains a downwardly tapering frustro-conical slip bowl recess 20 within which slips 13a, and 13b and 13c are received and supported. The three slips of course have corresponding outer partial frustro-conical surfaces 21 engageable with slip bowl surface 20, to earn the slips inwardly toward axis 18 and into engagement with pipe 12 upon downward movement of the slips into recess 20. The inner faces 22 of the slips have irregularized gripping surfaces for tightly gripping and supporting pipe 12 when the slips are in their FIG. 1 active positions.

The power slip unit 11 is desirably mounted to stationary portion 15 of the rotary table, by means of a bracket 23 rigidly welded or otherwise secured to section 15 and carrying a horizontal stationary mounting plate 24, bolted to the bracket at 25. Plate 24 projects laterally as seen in FIG. 1, and contains a circular opening 26 (FIG. 3) within which a mounting or support tube 27 is received and supported. Tube 27 is desirably of straight cylindrical configuration, centered about a vertical axis 28 which extends parallel to, but is offset laterally from, main axis 18 of the rotary table. Tube 27 may be secured to horizontal plate 24 in any suitable manner, as by welding at 29. A bottom horizontal wall 30 is bolted at 31 to the lower end of tube 27, and acts to support the apparatus contained within the tube.

The mechanism within tube 27 includes two relatively telescopically movable upper and lower tubes 32 and 33, the upper of which is actuated vertically relative to lower tube 33 and tube 27 by a piston and cylinder mechanism 34. All of the elements 32, 33 and 34 are free to turn about axis 28 as a unit, to correspondingly swing a slip mounting arm 35 carried by tube 32 about that axis.

Tube 33 may be considered as essentially a straight cylindrical vertical tube, except for the provision of two externally and slightly enlarged diameter portions 36 and 37 near its upper end. About surface 36, there are provided two bushing rings 38, supported on a shoulder 39 in tube 27, and acting to effectively journal the upper portion of tube 33 for rotation about axis 28 relative to tube 27. A seal ring 40 may be provided at the upper end of the bushings, together with a protective shielding ring 41.

At its lower end, tube 33 is closed by a horizontal bottom wall 42, bolted to tube 33 at 43, and having a downwardly projecting stub shaft portion 44 rotatably journalled within a boss 45 formed by bottom wall 30. More particularly, shaft 44 may be journalled within boss 45 by a ball bearing assembly 46, of a type acting both to center element 44 for its rotary motion about axis 28, and also to take downward thrusts in a manner supporting tube 33 within tube 27. The lower end of shaft 44 may be threaded for reception of the nut 47, which clamps the inner race of ball bearing 46 between a spacer element 48 and a shoulder 49 on element 44. Thus, tube 33 is effectively supported and guided for only rotary motion relative to main support tube 27.

The inner or upper tube 32 is telescopically received within tube 33, and projects upwardly therebeyond. Tube 32 is essentially of straight cylindrical configuration, centered about axis 28, and has rigidly attached to its lower end a ring 50 which carries several (typically three) circularly spaced guide rollers 51, rotatably mounted to bearings 52 which are rigidly secured to and project downwardly from ring 50. Since most of the forces exerted laterally by the lower end of tube 32, in use, are in a leftward direction as viewed in FIG. 3, one of the rollers 51 is preferably located at the center of the left side of the lower end of the tube. Rollers 51 turn about individual horizontal axes 53, with the rollers engaging and free to roll vertically along the inner surface of tube 33 as tube 32 moves upwardly and downwardly. Ring 50 and tube 32 are retained against rotation relative to tube 33 by means of a vertically elongated key or spline element 233 secured by bolts 333 to the inner side of tube 33, and received within a guide recess or key slot 250 in the relatively vertically movable ring 50.

To guide the upper end of tube 32 for its vertical movement relative to the tube 33, there may be provided a bushing 54 slidably guiding the outer cylindrical surface of tube'32. Bushing 54 may be carried any in suitable manner by an annular rigid element 55 which is typically bolted at 56 to a flange part 57 which is welded or otherwise rigidly secured to the upper end of tube 33. A retaining ring or washer 58 and two associated retainer elements 59 may be provided at the upper side of bushing 54, with elements 59 typically being bolted to member 55 at 159 (see FIG. 2).

The forces exerted laterally against tube 32 near its upper end are primarily in a rightward direction, as viewed in FIG. 3. Consequently, I provide at the center of the right side of tube 32 a roller 60, which is journalled by a bearing structure 61 rigidly secured to flange element 57, with the roller turning about a horizontal axis 62, so that the roller in effect rolls along the outer surface of tube 32 as the tube moves vertically. This roller thus provides a very low friction guide element for the upper portion of tube 32, taking most of the rightward force exerted against the upper end of tube 32 as a result of the weight of the slips and their carrier structure.

The vertically shiftable tube 32 carries the previously mentioned arm 35, and both of these parts are actuated vertically by the piston and cylinder mechanism 34 contained within tube 32. The cylinder 63 of this mechanism extends vertically and is centered about the previously mentioned axis 28, and has two upper and lower end walls 64 and 65 which are secured in fixed relation to side wall 63 of the cylinder in any suitable manner, as by locating pins represented at 66 and snap rings 266, and which end walls may be sealed with respect to the cylindrical side wall by O-rings 67. The bottom wall 65 of the cylinder is connected to lower wall 42 of tube 33 by by means of a projection 68 extending downwardly from wall 65, and a projection 69 extending upwardly from wall 42, with projections 68 and 69 secured together by a bolt or pin 70. The piston 71 within cylinder 63 has a piston rod 72 projecting upwardly through a bushing 73 carried by top wall 64 of the cylinder, and the piston rod is connected by a bolt or pin 74 to a lug 75 rigidly attached to and projecting downwardly from a top wall 76 of tube 32. This top wall 76 may be circular, as seen best in FIG. 2, and is secured by bolts or screws 77 and a keying pin 78 to a circular end portion 79 of arm 35. This portion 79 of arm 35 forms a cylindrical sleeve 80 extending downwardly about the upper end of tube 32, and rigidly secured to the tube by screws 81. Arm 35 projects horizontally to the right as viewed in FIGS. 2 and 3, and may be constructed in any suitable manner capable of giving to the arm suflicient strength and rigidity to withstand the forces exerted against it in use. For example, arm 35 may have an upper horizontal top wall 83, with two opposite parallel side walls 84 depending from the opposite edges of wall 83, and typically having a number of transverse strengthening partitions or walls 85 extending between walls 84 at spaced locations. A portion 86 of the arm near its free end may be widened somewhat, as seen in FIG. 2. Beyond this widened portion 86, the arm rigidly carries a slip carrier ring 82, which will be discussed in greater detail at a later point. Ring 82 may have a mounting flange portion 282 which is bolted to arm 35 by means of bolts represented at 283, having nuts 284.

Actuating pressure fluid is supplied to and withdrawn from the upper and lower portions of cylinder 34 through two flexible lines 87 and 187, which may be connected into openings in top and bottom walls 64 and 65 of the cylinder, and which extend downwardly through openings 88, 89 and 90 formed in walls 50, 42 and 30 respectively. The lower opening 90 is arcuate about axis 28, and has sufficient extent circularly about that axis to allow lines 87 and 187 to swing with tubes 32 and 33 through the extent required for actuating arm 35 between its active position of FIG. 2 and a laterally swung inactive position.

The weight of arm 35 and its supported slip elements is counterbalanced by the provision of a vertically movable counterbalance weight 91 disposed about the left side of tube 32 and element 55. As seen best in FIG. 2, this weight 91 is desirably essentially semicircular in horizontal cross-section, having an outer semicylindrical surface 92, and an inner surface 93 of partial cylindrical configuration. At its opposite ends, weight 91 is cut away to form diametrically opposed right angle recesses 94, defined at their radially outer sides by two arms 95 through which the shafts 96 of two rollers 97 extend. The two shafts 96 and their rollers 97 are desirably axially aligned, with their common axis 98 extending horizontally through a perpendicular to vertical axis 28 of the piston and cylinder mechanism and associated apparatus. Shafts 96 of these rollers are secured in their illustrated positions by nuts 99 attached to the outer ends of the shafts, with the rollers being maintained sufficiently loose for free rotation on the shafts about axis 98. Weight 91 desirably has the discussed essentially semicircular horizontal section along its entire vertical extent.

At a location spaced beneath the discussed rollers 97, weight 91 carries a second set of tapering frusto-conical rollers 100, which may be considered as identical with the two upper rollers 97, and are also centered about a common horizontal axis extending perpendicular to and intersecting vertical axis 28. Weight 91 is guided for straight line vertical movement relative to tube 33 by means of two parallel vertical tracks 101 secured rigidly of diametrically opposite sides of tube 33. Tracks 101 preferably have the H-shaped cross-section illustrated in FIG. 2, to form vertical tapering guide ways 102 within which the two pairs of rollers 97 and are received and guided for vertical movement. Tracks 101 may be secured to tube 33 by means of brackets 103 (FIG. 1), secured to the tube by bolts 104. Also, the tracks 101, in extending upwardly, may pass through or be received within recesses formed in element 55, and be welded to element 55, to further strengthen the rigid mounting of tracks 101 to tubes 33 and its carried element 55.

The counterbalancing force of weight 91 is transmitted to arm 35 by means of two parallel identical levers 105 which are mounted to pivot about a common horizontal axis 106 extending perpendicular to and intersecting vertical axis 28. To mount the levers for this pivotal movement, there may be rigidly attached to the upper end of each of the track elements 101, as by welding at 206, a bifurcated upwardly projecting bearing block 107 having a pin 108 extending through two halves 109 of this block and through the associated lever 105 received between those two halves. As will be apparent from FIG. 1, the pivotal axis 106 of levers 105 is located somewhat above the upper extremities 110 of the tracks 101, and as a result, the bifurcated bearing box 107 must project upwardly beyond the upper ends 110 of tracks 101 far enough to properly receive the lever mounting pivot pins 108.

The left ends of levers 105, as viewed in FIGS. 1 and 2, rotatably carry two rollers 111 centered about a common horizontal axis 112 extending parallel to axis 98 of rollers 97, and the axis of lower rollers 100. Rollers 111 are received within horizontal guide ways 113 formed in track elements 114 which are secured by bolts 115 to the upper horizontal surface 116 of counterweight 91. As will be apparent, guide ways 113 guide rollers 111 for only horizontal movement, in the directions designated by lines 117 of FIG. 2, relative to counterweight 91.

The right ends of levers 105 are similarly movably connected to the underside of arm 35 by means of two rollers 118 rotatably secured to the levers, and guided and confined within horizontal parallel guide ways 119 in two tracks 120 which are rigidly secured to the underside of arm 35. These tracks may typically be welded in the illustrated positions relative to arm 35. The rollers 118 turn about a common horizontal axis 121, which extends parallel to the previously mentioned axes 98 and 112. Preferably, the right hand portions of levers 105', between axes 106 and 121, are substantially longer than the left hand portions of the levers, between axes 106 and 112, the right hand portions desirably having a length which is at least about twice as long as the left hand portions. It is also noted that the right ends of the levers act upwardly against arm 35 at a location between its left mounting end and the right slip carrying end. By virtue of the shifting axis type of connection provided by rollers 111 and 118 at the left and right ends of levers 105, it is possible for these levers to swing about axis 106 and between any of the different possible positions of the levers, without causing horizontal shifting movement of arm 35 and its carried parts, or counterweight 91. Thus, arm 35 and the counterweight may both move in straight line verical paths even though they are interconnected by levers 105 in counterweighting relation.

The downward movement of arm 35 is limited by engagement of a stop element 122 (FIG. 3) with the upper horizontal surface of element 55. This stop element may take the form of a bolt having an upper enlarged head 123 guided for vertical movement within a passage 124 in the inner portion of arm 35, and yieldingly urged downwardly by a coil spring 125 which is retained in position by an upper cover plate 126 secured to arm 35 by screws or bolts 127 (FIG. 2). The bolt may be threadedly adjustable relative to its head element 123, to vary the position at which downward movement of arm 35 is limited. Also, element 123 may have a downwardly projecting portion 127 of reduced diameter, which is guided within an opening 128 to assist in guiding the stop structure for vertical movement. As will be apparent, when arm 35 approaches its lowermost position of FIG. 3, element 122 engages the upper surface of part 55, to yieldingly resist further downward movement, until such movement is completely halted by engagement of an ultimate stop member 129 with the under surface 130 of arm 35. A similar stop unit 130 may be provided in the lower portion of counterweight 91, and be spring urged downwardly relative thereto by a spring 131, to engage the upper surface of plate 24 in a manner limiting downward movement of the counte weight, and therefore upward movement of arm 35.

To now describe the construction of the apparatus carried at the right or free end of arm 35, this apparatus includes an annular mounting ring structure 82, rigidly attached to and forming an outer portion of arm 35, and to which there is rotatably mounted a slip carrier assembly 132. As seen best in FIG. 1, structure 82 includes an outer vertically extending cylindrical wall 133, to which there are rigidly attached, as by welding, an upper horizontal wall 134, and lower horizontal wall 135, and a depending cyindrical skirt 136 welded to the inner edge of wall The four walls 133, 134, 135 and 136, as well as the short upper wall 137, may all be annular about axis 18, and circularly continuous except at the location of a gate structure 138 (FIG. 2) which is adapted to swing from the full line position of FIG. 2 to the broken line position of that figure to pass vertical pipe 12 out of the slip supporting assembly when arm 35 and its carried parts are swung in a counterclockwise direction, as viewed in FIG. 2, about axis 28. As seen in FIG. 5, the vertical crosssection of gate 138 is identical with the verticalcross-section of the rest of structure 82, having walls 133a, 134a, 135a, 136a and 137a corresponding to walls 133 through 137 respectively of FIG. 1, so that the gate and structure 82 form together a completely circular track structure of uniform cross-section about its entire circular ex tent. Gate 138 is adapted to be swung between its open and closed positions of FIG. 2 by means of a handle 139 secured to the gate. As will be apparent, the gate is mounted to swing between its different positions by means of a hinge pin 140 extending vertically through hinge openings formed in handle 139 and an ear 141 attached to structure 82. The gate is releasably retained in closed position, by means of a lock pin 142 extending vertically through registering openings in an ear 143 on structure 82 and the second end of handle 139. The interengaging edges 144 and 145 of structure 82 and gate 138 are curved as shown, with edges 144 being centered about the axis of hinge element 140, so that the gate may swing freely between its open and closed positions.

The slip supporting element 132 (FIG. 1) forms essentially a ring centered about axis 18, but interrupted at one point to provide an open space between two ends 146 (FIG. 2) of the element. Except at the location of this interruption, element 132 has a uniform cross-section about its entire arcuate extent, that cross-section being illustrated in FIG. 1, to provide an upstanding vertical flange 147 to which a series of evenly circularly spaced rollers 148 are rotatably mounted by individual shafts 149, and to provide a second and horizontal flange 150 to which a series of evenly circularly spaced rollers 151 are rotatably mounted by short shafts 152. Rollers 148 turn about individual axes 153 extending radially of and intersecting vertical axis 18, while rollers 151 turn about individual circularly spaced axes 154 extending parallel to axis 18. Rollers 148 engage and roll along the upper surfaces of walls 135 and 135a, to rotatably support element 132, while rollers 151 engage and roll along the inner cylindrical surfaces of walls 136 and 136a, to eflFectively center element 132 about axis 18.

The slips 13a, 13b and 130 are suspended from element 132 by means of two identical projections or lugs 155 extending downwardly in spaced relation from element 132, and secured thereto, and movably engaged by a supported element 156 which is connected to the center one 13b of the three slips. Element 156 has triangular recesses 157 formed at its opposite sides, and defined by peripheral laterally extending flanges 158, with pins 159 carried by lugs 155 projecting into recesses 157 respectively at opposite sides of element 156. These pins are engageable with the upper inclined surfaces 160 of recesses 157, in a relation acting to cam element 156 to the left relative to element 132, when element 132 is lifted. This action is illustrated in FIG. 4, in which pins 159 are in engagement with surface 160, and have cammed element 156 and the carried slips to the left through part of their range of movement. The underside of element 156 is pivotally connected at 161 to slip 13b, to movably support that slip.

The three slips 13a, 13b and 130 may be of essentially similar configuration, each extending through about 126 circular degrees, so that the three slips together form essentially an annular slip structure. Slip 13a is pivotally connected to one side of slip 13b by a pivot pin 162 (FIG. 2), with the other side of slip 13b being pivoted to slip 130 by a second pivot pin 163. Pins 162 and 163 preferably extend vertically. The slips are yieldingly urged toward the broken line open position of FIG. 6 by a coil spring 164. The opposite ends of this spring are secured at 165 and 166 to upwardly projecting lugs formed on slips 13a and 13c respectively. Between these ends, the spring extends along the upper surfaces of the slips, and about their peripheries, in a manner such that the force exerted by the spring (which is under tension) tends to swing the opposed ends of slips 13a and 13c away from one another to an open position allowing pipe 12 to pass out of the slip assembly as the slips are removed laterally from the pipe. It is particularly noted that, at the locations of pivot pins 162 and 163, spring 164 extends about the radially outer sides of those pivot pins, being retained against radially inward movement at those locations by reception within cut-away areas or notches 167 formed in upstanding lugs 168 at the upper sides of the slips. Similarly, as seen in FIGS. 1 and 4, the spring is received within notches or cut-away areas 169 formed in an upstanding lug 170 carried by slip 13b, at the location of element 156. Thus, the slips are always yieldingly urged toward their open positions by spring 164, but may be manually otherwise held in closed positions as the slips are lowered into active engagement with the rotary table.

To now describe the manner of use of the illustrated apparatus, assume first of all that arm 35 is initially swung in a counterclockwise direction to the retracted broken line position 35a of FIG. 2. Also, assume that piston 71 is in its uppermost position, in which arm 35 is elevated above the position of FIGS. 1 and 3. If it is then desired to shift slips 13a, 13b and 130 to their active FIG. 1 positions, the first step is to manually swing arm 35 from the broken line FIG. 2 position to the full line FIG. 2 position. During this movement, gate 138 is open, so that the pipe 12 may pass through this gate, and similarly element 132 is turned to a position in which the pipe may pass through the opening formed between the ends 146 of element 132. Since the slips are retained in their open position by spring 164, and since they are so aligned that the opening formed between slips 13a and 13c is facing in the same direction as the opening between ends 146 of element 132 (toward the bottom of the sheet in FIG. 2), pipe 12 may pass through the opening formed between the slips, as the slips and the rest of the apparatus are all moved to the full line position of FIG. 2. The slips are then held in closed position against the tendency of spring 164, and pressure fluid is withdrawn from the lower end of cylinder 34 and forced into its upper end by a suitable pressure fluid supply and control unit 171 (FIG. 3), so that piston 71 will be actuated downwardly and cause corresponding movement of the arm 35. At the time of initiation of such downward movement, the pins 159 of FIG. 1 are received within the upper peak portions 172 of recesses 157, and the slips are therefore automatically held slightly away from pipe 12, and therefore can not yet be completely closed. As arm 35 moves downwardly, the slips engage tapering surface 20 of bushing 19 in the rotary table, and are cammed by that surface inwardly toward pipe 12. Ultimately, the slips reach the position of FIGS. 1 and 3, in which they completely and closely encircle and grip the pipe. Preferably, in this FIG. 1 position in which the slips support the pipe within the rotary table, pins 159 engage the lower horizontal edges of recesses 157, in a relation supporting element 132 high enough that rollers 148 no longer engage wall 135. Thus, a small space is provided between rollers 148 and element in the position of use of the slips, to assure proper engagement of the slips with the rotary table structure, and avoid suspension of the slips above a fully engaged position. Rollers 151 of course remain in engagement with wall 136 (or wall 136a) at all times, even in the FIG. 1 slightly elevated position of element 132.

When it is desired to remove the slips from their active positions, pressure fluid is supplied to the lower end of cylinder 63 and withdrawn from its upper end to actuate the piston and arm 35 upwardly, following which gate 138 may be opened, and the entire apparatus may be swung to the broken line position of FIG. 2, with slips 13a, 13b and 130 being automatically opened during the process by spring 164. In both raising and lowering arm 35, counterweight 91 substantially exactly balances the weight of arm 35 and its carried slips and other parts, so that the piston and cylinder mechanism may actuate the arm 35 in either direction with very little force. Also, as previously mentioned, this counterbalancing action is attained without interfering with the desired straight line vertical movement of arm 35, so that the slips may move into and out of their active positions with maximum effectiveness. Further, the weight 91 itself also moves directly vertically, in a straight line, by virtue of the manner in which it is guided for only vertical movement by rollers 97 and 100.

For releasably retaining the arm 35 in its FIG. 2 full line active position, when the slips are in use, there may be provided a latch mechanism such as the one represented at 172 in FIGS. 1 and 3. This mechanism may include a latch part 173 pivoted at 174 to a pair of ears 175 carried by ring 41, and receivable within a recess 176 formed in a keeper part 177 welded to plate 24. The latch element 173 is movable upwardly and downwardly by a handle 178, typically pivoted to element 173 at 179, and between the full line released position of FIG. 3, and the broken line lowered position in which element 173 is received within recess 176 and is engageable by two opposite side walls 180 thereof in a relation positively locking arm 35 in the FIG. 2 position. A second keeper part the same as part 177 may be provided on plate 24 at a location offset circularly from part 177, for latching engagement with element 173 in a relation holding arm 35 and the associated parts in a laterally swung retracted position.

We claim:

1. A power slip for use with a well drilling rotary table comprising a first tube adapted to extend vertically at a side of said table, a second vertically extending tube telescopically interfitting with said first tube and actuable vertically relative thereto, a carrier structure carried by said second tube and movable vertically therewith, slips carried by said carrier structure, a generally vertically extending piston and cylinder mechanism within said tubes for actuating said second tube and carrier structure vertically relative to said first tube, a third tube having a generally vertical axis and disposed about said first tube and mounting it and said second tube and said carrier structure and slips for swinging movement together about essentially said generally vertical axis and between active and retracted positions of the slips, and a counterbalanc- 9 ing means for exerting an upward counterbalancing force against said carrier structure.

2. A power slip for use with a Well drilling rotary table comprising a first tube adapted to extend vertically at a side of said table, a second vertically extending tube telescopically interfitting with said first tube and actuable vertically relative thereto, a carrier structure carried by said second tube and movable vertically therewith, said carrier structure including an arm projecting to a location over said table, slips carried by said carrier structure, a generally vertically extending piston and cylinder mechanism within said tubes for actuating said second tube and carrier structure vertically relative to said first tube, a third tube having a generally vertical axis and disposed about said first tube and mounting it and said second tube and said carrier structure and slips for swinging movement together about essentially said generally vertical axis and between active and retracted positions of the slips, and counterbalancing means for exerting an upward counterbalancing force against said carrier structure, said counterbalancing means including a pivotally mounted lever acting upwardly against said arm at a location between said tubes and said slips, and a counterweight acting downwardly against said lever.

3. A power slip for use with a Well drilling rotary table comprising a first tube adapted to extend vertically at a side of said table, a second vertically extending tube telescopically interfitting with said first tube and actuable vertically relative thereto, a carrier structure carried by said second tube and movable vertically therewith, said carrier structure including an arm projecting to a location over said table, slips carried by said carrier structure, a generally vertically extending piston and cylinder mechanism Within said tubes for actuating said second tube and carrier structure vertically relative to said first tube, a third tube having a generally vertical axis and disposed about said first tube and mounting it and said second tube and said carrier structure and slips for swinging movement together about essentially said generally vertical axis and between active and retracted positions of the slips, and a counterbalancing means for exerting an upward counterbalancing force against said carrier structure, said counterbalancing means including a pivotally mounted lever acting upwardly against said arm at a location between said tubes and said slips, a counterweight mounted to said first tube for straight line vertical movement, a lever mounted to said first tube for pivotal movement, and two pivot connections attaching said lever at spaced locations to said arm and said weight respectively for pivotal movement relative thereto about two spaced axes, said pivot connections being constructed to enable said two axes to shift horizontally upon pivotal movement of the lever.

A. A slip assembly for use with a rotary table, said assembly comprising a carrier unit, a rotating unit supported by said carrier unit for rotation relative thereto about an essentially vertical axis, slips carried by and depending from said rotating unit for engaging and gripping a well pipe, at set of circularly spaced first rollers carried by a first of said units, a generally vertically facing track surface on a second of said units engageable by said rollers in a relation rotatably supporting said rotating unit from said carrier unit, a set of circularly spaced second rollers carried by one of said units, and a second track surface on the other of said units facing generally radially of said axis and engageable by said second rollers in a relation retaining said rotating unit against shifting movement relative to said carrier unit transversely of said axis, said first rollers being free for vertical movement out of engagement with said vertically facing track surface when said slips are supported by a rotary table and While said second rollers remain in engagement with said second track surface.

5. A slip assembly for use with a rotary table, said assembly comprising a carrier unit, a rotating unit supported by said carrier unit for rotation relative thereto about an essentially vertical axis, slips carried by and depending from said rotating unit for engaging and gripping a well pipe, a set of circularly spaced first rollers mounted to said rotating unit for rotation relative thereto about individual essentially horizontal axes, a set of circularly spaced second rollers mounted to said rotating unit for rotation relative thereto about individual essentially vertical axes, a first upwardly facing essentially annular track surface on said carrier unit engaged by said first rollers to rotatably support said rotating unit, and a second radially facing track surface engaged by said second rollers in a relation retaining 'said rotating unit against movement relative to said carrier unit transversely of said axis, said first rollers being free for upward movement out of engagement with said upwardly facing track surface when said slips are supported by a rotary table and while said second rollers remain in engagement with said second track surface.

6. A slip assembly comprising a carrier unit, a rotating unit supported by said carrier unit for rotation relative thereto about an essentially vertical axis, slips carried by said rotating unit for engaging and gripping a well pipe, a set of circularly spaced first rollers mounted to said rotating unit for rotation relative thereto about individual essentially horizontal axes, a set of circularly spaced second rollers mounted to said rotating unit for rotation relative thereto about individual essentially vertical axes, a first upwardly facing essentially annular track surface on said carrier unit engaged by said first rollers to rotatably support said rotating unit, and a second radially facing track surface engaged by said second rollers in a relation retaining said rotating unit against movement relative to said carrier unit transversely of said axis, said carrier unit including a main portion forming a main portion of both of said track surfaces but having an interruption at one side of said axis, and a gate forming portions of both of said track surfaces at the location of said interruption and movable relative to said main portion between open and closed positions.

7. A power slip for use with a well drilling rotary table comprising a support to be mounted at a side of said rotary table, an arm movably mounted to said support at said side of the table and projecting generally horizontally from said side of the table to a location over the table, slips carried by and connected to said arm near a first end thereof at said location over the table and spaced horizontally from said support, pivotal and axial movement connecting means attaching said arm near a second end thereof to said support for generally horizontal lateral swinging movement about a generally vertical axis at essentially the location of said support to retract the slips to a side 'of the table and for straight line up and down axial movement bodily and with the arm remaining in fixed orientation with respect to the horizontal, power operated means for actuating said arm vertically, and counterbalancing means exerting an upward counterbalancing force against said arm at a loctaion horizontally between the locations of said support and said slips and intermediate the points of connection of said arm to said support and said slips.

8. A power slip for use with a well drilling rotary table comprising a support to be mounted at a side of said rotary table, an arm movably mounted to said support at said side of the table and projecting generally horizontally from said side of the table to a location over the table, slips carried by and connected to said arm near a first end thereof at said location over the table and spaced horizontally from said support, pivotal and axial movement connecting means attaching said arm near a second end thereof to said support for generally horizontal lateral swinging movement about a generally vertical axis at essentially the loctaion of said support to retract the slips to a side of the table and for straight line up and down axial movement bodily and with the arm remaining in fixed orientation with respect to the horizontal, power operated means for actuating said arm vertically, and counterbalancing means exerting an upward counterbalancing force against said arm at a location horizontally between the locations of said support and said slips and intermediate the points of connection of said arm to said support and said slips, said counterbalancing means including a pivotally mounted lever formed separately from said arm and acting thereagainst at said location intermediate said points of connection to the support and slips, and means for exerting force against said lever in a direction to bear upwardly against said arm.

9. A power slip for use with a well drilling rotary table comprising a first structure to be mounted at a side of said rotary table, a carrier structure, slips carried by said carrier structure, means mounting said carrier structure for straight line vertical movement relative to said first structure without horizontal shifting of the carrier structure during said vertical movement, means for actuating said carrier structure vertically, and counterbalancing means exerting a force against said carrier structure counterbalancing the weight thereof, said counterbalancing means including a swinging lever structure, first pivot means connecting said lever structure at a first location to said carrier structure for pivotal movement relative thereto about a first axis, second pivot means connecting said lever structure at a second location to said first structure for fulcrumming pivotal movement about a second axis, and means exerting a counterbalancing force against said lever structure and through it against said carrier structure, one of said first and second pivot means being of a shifting axis type constructed to enable said axis thereof to shift horizontally relative to one of the two structures interconnected thereby to compensate for the swinging of said lever structure and thereby avoid interference by the lever structure with said straight line vertical movement of the carrier structure.

10. A power slip for use with a well drilling rotary table comprising a first structure .to be mounted at a side of said rotary table, a carrier structure, slips carried by said carrier structure, means mounting said carrier structure for straight line vertical movement relative to said first structure without horizontal shifting of the carrier structure during said vertical movement, means for actuating said carrier structure vertically, and counterbalancing means exerting a force against said carrier structure counterbalancing the weight thereof, said counterbalancing means including a swinging lever structure, first pivot means connecting said lever structure at a first location to said carrier structure for pivotal movement relative thereto about a first axis, second pivot means connecting said lever structure at a second location to said first structure for fulcrurnming pivotal movement about a second axis, and a counterweight exerting a counterbalancing force downwardly against said lever structure and through it against said carrier structure, means mounting said counterweight structure for straight line vertical movement without horizontal shifting movement, and third pivot means connecting said lever structure at a third location to said counterweight structure for pivotal movement relative thereto about a third axis, two of said three pivot means being of a shifting axis type constructed to enable said axis thereof to shift horizontally relative to one ofthe two structures interconnected thereby to compensate for the swinging of said lever structure and thereby avoid interference by the lever structure with said straight line vertical movement of the carrier structure and counterweight structure.

11. A power slip for use" with a well drilling rotary table comprising a first structure to be mounted at a side of said rotary table, a carrier structure, slips carried by said carrier structure, means mounting said carrier structure for straight line vertical movement relative to said first structure without horizontal shifting of the carrier structure during said vertical movement, means for actuating said carrier structure vertically, and counterbalancing means exerting a force against said carrier structure counterbalancing the weight thereof, said counterbalancing means including a swinging lever structure, first pivot means connecting said lever structure at a first location to said carrier structure for pivotal movement relative thereto about a first axis, second pivot means connecting said lever structure at a second location to said first structure for fulcrumming pivotal movement about a second axis, and a counterweight exerting a counterbalancing force downwardly against said lever structure and through it against said carrier structure, means mounting said counterweight structure for straight line vertical movement without horizontal shifting movement, and third pivot means connecting said lever structure at a third location to said counterweight structure for pivotal movement relative thereto about a third axis, said first and third pivot means being of a shifting axis type constructed to enable said axis thereof to shift horizontally relative to one of the two structures interconnected thereby to compensate for the swinging of said lever structure and thereby avoid interference by the lever structure with said straight line vertical movement of the carrier structure and counterweight structure.

12. A power slip for use with a well drilling rotary table comprising a support to be mounted at a side of said rotary table, an arm movably mounted to said support at said side of the table and projecting generally horizontally from said side of the table to a location over the table, slips carried by and connected to said arm near a first end thereof at said location over the table and spaced horizontally from said support, pivotal and axial movement connecting means attaching said arm near a second end thereof to said support for generally horizontal lateral swinging movement about a generally vertical axis at essentially the location of said support to retract the slips to a side of the table and for straight line up and down axial movement bodily and with the arm remaining in fixed orientation with respect to the horizontal, power operated means for actuating said arm vertically, and counterbalancing means exerting an upward counterbalancing force against said arm at a location horizontally between the locations of said support and said slips and intermediate the points of connection of said arm to said support and said slips, said counterbalancing means including a lever, a first pivotal connection connecting said lever to said arm at said location between the support and slips for pivotal movement about a first generally horizontal axis, a second pivotal connection attaching said lever at a different location to said support for fulcrumming pivotal movement about a second generally horizontal axis, and means exerting a counterbalancing force against said lever and through it against said arm, one of said pivotal connections being of a shifting axis type constructed to enable said axis thereof to shift horizontally relative to one of the two parts interconnected thereby to compensate for the swinging movement of the lever and thereby avoid in terference by the lever with said straight line vertical movement of the arm.

13. A power slip for use with a well drilling rotary table comprising a support to be mounted at a side of said rotary table, an arm movably mounted to said support at said side of the table and projecting generally horizontally from said side of the table to a location over the table, slips carried by and connected to said arm near a first end thereof at said location over the table and spaced horizontally from said support, pivotal and axial movement connecting means attaching said arm near a second end thereof to said support for generally horizontal lateral swinging movement about a generally vertical axis at essentially the location of said support to retract the slips to a side of the table and for straight line up and down axial movement bodily and with the arm remaining in fixed orientation with respect to the horizontal, power operated means for actuating said arm vertically, and counterbalancing means exerting an upward counterbalancing force against said arm at a location horizontally between the locations of said support and said slips and intermediate the points of connection of said arm to said support and said slips, said counterbalancing means including a lever, a first pivotal connection connecting said lever to said arm at said location between the support and slips for pivotal movement about a first generally horizontal axis, a second pivotal connection attaching said lever at a different location to said support for fulcrumming pivotal movement about a second generally horizontal axis, a counterweight exerting a counterbalancing force against said lever and through it against said arm, means mounting said counterweight to said support for straight line vertical movement without horizontal shifting movement, and a third pivotal connection attaching said lever at another locattion to said counterweight for pivotal movement relative thereto about a third generally horizontal axis, said first and third pivotal connections both being of a shifting axis pin and slot type enabling horizontal shifting movement of said first and third axes relative to said arm and counterweight respectively to avoid interference by the lever with said straight line vertical movement of the arm and counterweight.

14. The combination comprising a series of pipe gripping slips for engaging and gripping different sides of a pipe, a plurality of hinges interconnecting successive slips for relative pivotal movement in opening and closing directions about spaced essentially vertical axes, and a coil spring under tension connected at opposite ends to a pair of end ones of said series of slips and extending along the radially outer sides of said series of slips under tension and extending past said hinges at the radially outer sides thereof at a location to yieldingly urge said slips in said opening direction.

References Cited by the Examiner UNITED STATES PATENTS 1,110,368 9/14 Young 292-18 1,113,132 10/14 McAllister 24263 X 1,179,500 4/16 Brown.

1,356,458 10/20 Moody 24263 1,656,864 1/ 28 Martin.

2,340,597 2/44 Kelley 24263 2,393,603 1/46 Beeth.

2,575,356 11/51 Mullinix 24-263 2,575,649 11/51 Abegg 24263 2,698,734 1/55 Tremolada et a1. 24263 2,772,106 11/56 Semelka 29218 DONLEY J. STOCKING, Primary Examiner.

SAMUEL KOREN, Examiner. 

1. A POWER SLIP FOR USE WITH A WELL DRILLING ROTARY TABLE COMPRISING A FIRST TUBE ADAPTED TO EXTEND VERTICALLY AT A SIDE OF SAID TABLE, A SECOND VERTICALLY EXTENDING TUBE TELESCOPICALLY INTERFITTING WITH SAID FIRST TUBE AND ACTUATABLE VERTICALLY RELATIVE THERETO, A CARRIER STRUCTURE CARRIED BY SAID SECOND TUBE AND MOVABLE VERTICALLY THEREWITH, SLIPS CARRIED BY SAID CARRIER STRUCTURE, A GENERALLY VERTICALLY EXTENDING PISTON AND CYLINDER MECHANISM WITHIN SAID TUBES FOR ACTUATING SAID SECOND TUBE AND CARRIER STRUCTURE VERTICALLY RELATIVE TO SAID FIRST TUBE, A THIRD HAVING A GENERALLY VERTICAL AXIS AND DISPOSED ABOUT SAID FIRST TUBE 